The role of cryptic nutrient cycling within sinking particles on trace element transport in oxygen minimum zones

下沉颗粒内隐秘养分循环对最低氧区微量元素运输的作用

• 批准号: 1636332
• 负责人: James Moffett
• 金额: $ 83.9万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1636332&HistoricalAwards=false
• 关键词: role; cryptic; nutrient; cycling; within

The major process controlling the internal cycling of biologically active trace metals in the oceans is through uptake onto and remineralization from sinking particles. Uptake can occur through active biological uptake into living cells as micronutrients, or chemical adsorption onto sinking materials. This latter process is often referred to as scavenging. The relative importance of these processes is often unclear, especially for elements that are both biologically active and also "particle reactive." The latter characteristic is associated with sparing solubility in seawater and the formation of strong complexes with surface sites, with examples such as iron. Recent evidence suggests that the simplistic view of a sinking particle as a passive surface for metal complexation may require some revision. Investigators James Moffett and Seth John propose to study the chemistry of transition metals within large sinking particles and the resultant effects on metal biogeochemical cycling. They will collaborate with a group at the University of Washington, recently funded to study the microbiology and molecular biology of these particles. The central hypothesis of this project is that reducing microbial microenvironments within large particles support high rates of nitrogen and sulfur cycling, greatly enhancing the particles' influence on metal chemistry. The investigators will study these processes in the Eastern Tropical North Pacific Oxygen Minimum Zone (OMZ). This regime was selected because of the wide range of redox conditions in the water column, and strong preliminary evidence that microenvironments within sinking particles have major biogeochemical impacts.The primary objective is to investigate the interactions of metals with particles containing microenvironments that are more highly reducing than the surrounding waters. Such microenvironments arise when the prevailing terminal electron acceptor (oxygen, or nitrate in oxygen minimum zones) becomes depleted and alternative terminal electron acceptors are utilized. Within reducing microenvironments metal redox state and coordination chemistry are different from the bulk water column, and these microenvironments may dominate metal particle interactions. For example, reduction of sulfate to sulfide could bind metals that form strong sulfide complexes, such as cadmium and zinc, processes previously thought to be confined to sulfidic environments. Reducing microenvironments may account for the production of reduced species such as iron(II), even when their formation is thermodynamically unfavorable in the bulk water column. Tasks include observational characterization of dissolved and particulate trace metals and stable isotopes in the study area, sampling and in situ manipulation of particles using large-dimension sediment traps, shipboard experimental incubations under a range of redox conditions, and modeling, providing insight from microscopic to global scales. The metal chemistry data will be interpreted within a rich context of complimentary data including rates of nitrogen and sulfur cycling, phylogenetics and proteomic characterization of the concentration of key enzymes. Broader impacts include training of a postdoctoral scientist, international collaborations with Mexican scientists, and involvement of undergraduate students in the research.

控制海洋中生物活性微量金属内部循环的主要过程是通过沉没颗粒的吸收和再矿化。吸收可以通过活性生物吸收作为微量营养素进入活细胞，或化学吸附到下沉材料上。后一个过程通常称为清除。这些过程的相对重要性通常不清楚，特别是对于既具有生物活性又具有“粒子反应性”的元素。后一个特性与在海水中的低溶解度以及与表面位点（例如铁）形成强复合物有关。最近的证据表明，将下沉颗粒视为金属络合的被动表面的简单化观点可能需要一些修改。研究人员詹姆斯·莫菲特和塞斯·约翰提议研究大下沉颗粒内过渡金属的化学性质及其对金属生物地球化学循环的影响。他们将与华盛顿大学的一个小组合作，该小组最近获得资助来研究这些颗粒的微生物学和分子生物学。该项目的中心假设是，减少大颗粒内的微生物微环境可支持氮和硫的高循环率，从而大大增强颗粒对金属化学的影响。研究人员将在东部热带北太平洋最低氧气区（OMZ）研究这些过程。选择这种方案是因为水柱中的氧化还原条件范围广泛，并且初步证据表明下沉颗粒内的微环境具有重大的生物地球化学影响。主要目标是研究金属与含有更高还原性微环境的颗粒的相互作用比周围水域。当主要的末端电子受体（氧气或氧气最小区域中的硝酸盐）耗尽并且使用替代末端电子受体时，就会出现这种微环境。在还原性微环境中，金属氧化还原态和配位化学与本体水柱不同，这些微环境可能主导金属颗粒相互作用。例如，硫酸盐还原成硫化物可以与金属结合，形成强硫化物络合物，例如镉和锌，这一过程以前被认为仅限于硫化物环境。减少微环境可能会导致铁（II）等还原物质的产生，即使它们在大量水柱中的形成在热力学上是不利的。任务包括研究区域中溶解和颗粒痕量金属以及稳定同位素的观测表征、使用大尺寸沉积物捕集器对颗粒进行采样和原位操纵、在一系列氧化还原条件下进行船上实验孵化以及建模，提供从微观到微观的洞察。全球规模。金属化学数据将在丰富的补充数据背景下进行解释，包括氮和硫循环速率、系统发育和关键酶浓度的蛋白质组表征。更广泛的影响包括博士后科学家的培训、与墨西哥科学家的国际合作以及本科生参与研究。

项目成果

The role of water masses in shaping the distribution of redox active compounds in the Eastern Tropical North Pacific oxygen deficient zone and influencing low oxygen concentrations in the eastern Pacific Ocean

水团在塑造东部热带北太平洋缺氧区氧化还原活性化合物分布和影响东太平洋低氧浓度中的作用

• DOI: 10.1002/lno.11412
• 发表时间: 2020-02-06
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: N. Evans;Elisabeth L. Boles;Jarek V. Kwiecinski;Susan Mullen;M. Wolf;A. Devol;R. Moriyasu;S. Nam;A. R. Babbin;J. Moffett
• 通讯作者: J. Moffett

Limited iodate reduction in shipboard seawater incubations from the Eastern Tropical North Pacific oxygen deficient zone

东部热带北太平洋缺氧区船上海水孵化中的碘酸盐减少有限

• DOI: 10.1016/j.epsl.2020.116676
• 发表时间: 2021-01-15
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: D. Hardisty;T. Horner;N. Evans;R. Moriyasu;A. R. Babbin;S. Wankel;J. Moffett;S. Nielsen
• 通讯作者: S. Nielsen

Determination of iron(II) by chemiluminescence using masking ligands to distinguish interferences

使用掩蔽配体通过化学发光法测定铁 (II) 以区分干扰

• DOI: 10.1002/lom3.10279
• 发表时间: 2018-09
• 期刊: Limnology and Oceanography: Methods
• 作者: Bolster, K. M.;Heller, M. I.;Moffett, J. W.
• 通讯作者: Moffett, J. W.

The Distribution and Redox Speciation of Iodine in the Eastern Tropical North Pacific Ocean

热带北太平洋东部碘的分布和氧化还原形态

• DOI: 10.1029/2019gb006302
• 发表时间: 2020-02-01
• 期刊: Global Biogeochemical Cycles
• 影响因子: 5.2
• 作者: R. Moriyasu;N. Evans;K. Bolster;D. Hardisty;J. Moffett
• 通讯作者: J. Moffett